1. Field
This application relates to a phosphor and a method for manufacturing the phosphor.
2. Description of Related Art
Recently, a phosphor capable of performing a photoconversion has been built in a light emitting device such as LED lighting, a display, and other light emitting devices.
For example, in the LED lighting, development of coating a semiconductor chip with the phosphor has been made by adding in a dropwise fashion a dispersion of the phosphor inside a silicone resin or other medium on an InGaN-based semiconductor chip emitting light close to blue light or ultraviolet light, which is regarded to be promising as an excitation light source.
Light emitted from the phosphor excited by light emitted from the InGaN-based semiconductor modifies the color or tone of light emitted from the LED lighting.
The photoluminescence characteristics of the phosphor play a very important role in terms of characteristics of the light emitting device. In other words, the characteristics of the light emitting device are determined by the photoluminescence characteristics of the phosphor performing the photoconversion.
Currently, such light emitting devices mainly use a phosphor excited by visible light, for example, Y3Al12O5:Ce emitting yellow light, CaAlSiN3:Eu emitting red light, and other phosphors excited by visible light and emitting various colors of light. Such phosphors are known to have the best photoluminescence characteristics when their particle diameter is within a range of several μm to tens of μm.
On the other hand, a phosphor particulate having an average particle diameter of less than 1 μm lacks a crystalline structure and has many defects, causing a large deterioration in luminance due to insufficient dispersion of an activator element, and is known to be inappropriate for a light emitting device generally using an LED and a phosphor such as lighting, a display, or other light emitting device.
However, the phosphor particulate having an average particle diameter of less than about 1 μm has recently been in increasing demand for various uses. For example, when applied to a conventional fluorescent lamp, the phosphor particulate having an average particle diameter of less than about 1 μm exhibits an excellent coating performance compared to a phosphor having an average particle diameter of tens of μm. In addition, when applied to an LED lighting package, excellent dispersity, a small load, and improved photodispersity may be obtained compared with the phosphor having an average particle diameter of tens of μm.
However, the luminous efficiency of an oxynitride phosphor particulate or a nitride phosphor particulate having an average particle diameter of less than about 1 μm needs to be improved to match the luminance efficiency of a phosphor generally used for an LED lighting package. Accordingly, research on improving the nephelauxetic effects of the phosphor particulate is ongoing. Specifically, to maximize the nephelauxetic effects by sufficiently increasing crystal field splitting in an activator ion such as Eu2+, Ce3+, or other activator ion, the oxynitride phosphor particulate or the nitride phosphor particulate should contain a nitrogen anion.
However, a phosphor can be currently manufactured to have an average particle diameter of several μm to tens of μm, but a phosphor particulate having an average particle diameter of less than about 1 μm and a method of preparing the same for a high performance light emitting device or a method of manufacturing the same have not yet been developed.